Fellow Shadow Watchers. Again with apologies but I would hate to have inflicted the same unresolved problem on others - like waiting for the upstairs flat dweller to throw down the other shoe!
"I.I.T.S.F.O.F." = "Imitation is the sincerest form of flattery" Many thanks to Mark Wrigley for putting me out of my misery! - and to others who kindly responded. Tony Moss.